The present invention relates to stripe electrical contacts on electroluminescent semiconductor devices and more specifically to stripe electrical contacts providing uniform current density in an electroluminescent semiconductor device.
It is well known in the field of electroluminescent semiconductor devices such as lasers and light emitting diodes (LED) to use stripe contacts to restrict the current flow to only a portion of the device. Thus, the light emission will come from only a small portion of the device's emitting surface. Typically, the stripe contact extends across a surface of the device approximately perpendicular to the emitting surface. The pattern of current flowing from the stripe contact usually flares out as the current flows away from the stripe contact. How much the current pattern flares out is dependent on the conductivity of the semiconductor material of the device and the geometry of the contact. However, the current density along the current flow pattern from one flared side to the opposite flared side is not uniform. The current density is highest in the center of the current flow pattern, i.e., directly under the center of the stripe contact, and continues to decrease moving out toward the flared sides of the current flow pattern.
This non-uniformity of the current density in the recombination region of a semiconductor laser or LED results in non-uniform radiation generation in the semiconductor device. Also, non-uniform current density caused non-uniform heating in the recombination region of the semiconductor device, reducing efficiency and device lifetime. Therefore, it would be most desirable in the field of semiconductor lasers and LED's to have a stripe contact which can provide a pattern of current flow of a uniform current density in the recombination region.